Innovative facility to test interaction of soil and structures during simulated earthquakes
The Soil Box System – the largest in the U.S. and comparable in size to the largest one in the world – is a collaboration with the University of Nevada, Reno, Lawrence Berkeley National Laboratory, and its design and construction were supported by the U.S. Department of Energy.
University of Nevada, Reno engineering capability creates realistic earthquakes in the lab, pairs with collaborators’ supercomputing expertise to lead to resilient buildings and infrastructure
RENO, Nev. – A new era in large-scale earthquake engineering testing is ushered in with the completion of the massive, innovative Large-Scale Laminar Soil Box System, part of the University of Nevada, Reno’s world-renowned earthquake engineering complex. It provides an unprecedented and innovative experimental facility for evaluating the complex manner in which structural systems like buildings and bridges interact with the surrounding soil during an earthquake.
The Soil Box System – the largest in the U.S. and comparable in size to the largest one in the world – is a collaboration with the University and Lawrence Berkeley National Laboratory, and its design and construction were supported by the U.S. Department of Energy. Studies conducted with the Soil Box System will provide data for another effort, EQSIM: an ongoing collaboration between scientists at Berkeley Lab, Lawrence Livermore National Laboratory and the University of Nevada, Reno to develop realistic, highly detailed earthquake simulations using DOE’s supercomputers.
The collaborators celebrated the completion of construction of the Soil Box System on Sept. 15, 2022, with a demonstration of the 24-foot square, 25-foot tall integrated shake table and soil box that has the capacity to hold 350 tons of soil, plus a structure on top, when experiments are conducted.
The system was designed, engineered and constructed by faculty and technicians of the University’s Center for Civil Engineering Earthquake Research, with the support of area contractors and manufacturers.
The facility will become a resource for DOE researchers focused on seismic safety as well as scientists across academia and industry.
“It’s important for DOE and NNSA to invest in this work to ensure that the large, complicated, one-of-a-kind facilities we build are designed to protect the country’s research, defense, and energy-generation needs, but the findings have an added benefit of helping engineers and architects in industry and the private sector build a wide range of earthquake-resilient structures,” James McConnell, associate principal deputy administrator for DOE’s National Nuclear Security Administration, said.
The two projects funded by the DOE seek to fill in the gaps and provide resources for researchers and engineers to study earthquakes across scales, from the initiation of seismic waves propagating outward from the earthquake fault, to the interactions between shaking soil and individual buildings.
“These projects are synergistic,” said David McCallen, project leader, director of the University’s Center for Civil Earthquake Engineering Research and a senior scientist in Berkeley Lab’s Earth and Environmental Sciences Area. “The Soil Box System is helping us understand and refine how we model the complex interaction between the soil and a structure. Our objective is to make realistic models of specific interactions – for example, what happens to a 20-story building very near California’s Hayward fault during a large-magnitude earthquake? – and add them to our existing large-scale simulations. We want to model all the way from the fault rupture through the ground to the structure to see how buildings and other infrastructure in an entire region will respond.”
Innovative Design
The Soil Box System project was launched in 2015 out of a need to safeguard Department of Energy buildings that hold sensitive scientific instruments against any potential earthquake scenario. “It was driven by how little we knew about the way soil surrounding the foundation of a building affects its performance during an earthquake,” said Soil Box principal investigator Ian Buckle, a Foundation professor in the University’s Department of Civil & Environmental Engineering.
“For buildings on shallow foundations, there’s probably not much effect. But for those with deeper foundations, such as nuclear facilities and long-span bridges, the answer is perhaps a great deal,” Buckle said.
The 15-foot-high, 21.5-foot-wide box sits on the 24-foot square shaking platform controlled by eight hydraulic actuators used to generate horizontal motions. The soil container has 19 layers, called laminates, that are each supported on bespoke elastomeric (rubber-like) bearings so that soil layers can move relative to each other like soil does during actual earthquakes.
The system can displace and accelerate 350 tons of soil in two directions simultaneously with the same force as a strong earthquake, and is so powerful that the designers had to build in safeguards to prevent it from destroying itself during experiments. The hydraulics are controlled by custom software and the box is equipped with a suite of sensors so that the scientists can gather detailed datasets to feed into their computer simulations.
A new generation of supercomputing
Current models of earthquake properties rely on approximations and simplifications due, in part, to the lack of real-world data on the fundamental physics involved, but also because very few computers on the planet are actually capable of running earthquake simulations at the fidelity required to perform infrastructure damage assessments.
McCallen and his EQSIM colleagues have been using the Summit supercomputer at Oak Ridge National Laboratory and the Perlmutter supercomputer at Berkeley Lab to develop very large, detailed models – like their simulations of the San Francisco Bay Area for M7 Hayward fault earthquakes – which has 391 billion model grid points. They will also soon start working on an even more capable platform – the newly launched Frontier supercomputer, also at Oak Ridge. Frontier is the first computer system to break the exascale barrier, meaning that it is capable of calculating at least a billion billion (also known as a quintillion, or 1018) operations per second, and is currently ranked as the world’s most powerful supercomputer.
Using these exceptionally fast machines, the longstanding goal of rupture-to-structure modeling is now becoming a computational reality. Their simulations will then be made available to the public through the Pacific Earthquake Engineering Research Center’s open-access database of simulations. PEER is a multi-institution research center focused on performance-based earthquake engineering, led by UC Berkeley.
“With this new collaboration with Berkeley Lab, we continue to lead in the area of seismic inquiry, and the safety and resiliency of infrastructures,” College of Engineering Dean Erick Jones said. “Together, our work will inform the DOE’s interests in facility safety, but the Laminar Soil Box also will be available to a broad spectrum of earthquake safety stakeholders. This corresponds to the University’s mission as a land-grant university to better humanity through education, research and outreach.”
The University of Nevada, Reno’s internationally renowned earthquake engineering complex conducts research, testing and analysis for new designs and materials for large structures, ultimately helping make buildings, bridges and highways safer. This Soil Box System adds to the complex’s capacity of four large-scale shake tables with 30,000 square feet of space for experiments. The complex comprises the largest and most versatile large-scale structures earthquaksoile/seismic simulation facility in the U.S.
The Soil Box project has been supported by the DOE’s Office of Environment, Health, Safety and Security’s Nuclear Safety Research and Development Program, and the National Nuclear Security Administration. The EQSIM is an application development project within the DOE Exascale Computing Project.
The University of Nevada, Reno, is a public research university that is committed to the promise of a future powered by knowledge. Nevada’s land-grant university founded in 1874, the University serves 21,000 students. The University is a comprehensive, doctoral university, classified as an R1 institution with very high research activity by the Carnegie Classification of Institutions of Higher Education. Additionally, it has attained the prestigious “Carnegie Engaged” classification, reflecting its student and institutional impact on civic engagement and service, fostered by extensive community and statewide collaborations. More than $800 million in advanced labs, residence halls and facilities has been invested on campus since 2009. It is home to the University of Nevada, Reno School of Medicine and Wolf Pack Athletics, maintains a statewide outreach mission and presence through programs such as the University of Nevada, Reno Extension, Nevada Bureau of Mines and Geology, Small Business Development Center, Nevada Seismological Laboratory, and is part of the Nevada System of Higher Education. Through a commitment to world-improving research, student success and outreach benefiting the communities and businesses of Nevada, the University has impact across the state and around the world. For more information, visit www.unr.edu.
